The present invention relates to a process and apparatus for catalytically reacting a gas containing a reducing component or components with water vapor in a pressure reactor of the type including an external pressure resistant container as well as an inner container containing a volume of catalyst.
Processes and apparatuses of the above type are known and are frequently employed for CO-methanization reactions and for CO-conversion reactions, as well as for reactions employing water vapor and other gases containing reducing components. Temperatures involved in such reactions are normally in the range of from approximately 623.degree. K. to 723.degree. K. (i.e. from 350.degree. C. to 450.degree. C.). The pressures involved in such reactions normally amount to approximately between 10 and 100 bar. Under such reaction conditions, i.e. quite high temperatures and pressures, the reducing components of the gases involved, for example carbon monoxide and hydrogen, may readily attack and penetrate the wall of the pressure resistant container, if such container is made of simple steel material, thereby leading to brittleness of the material and substantial premature corrosion damage.
Previous attempts to avoid such corrosion damage have involved the use of special alloy steels, particularly of the so-called pressure and hydrogen resistant type steels. Such special alloys steels are capable of withstanding the above described stresses. However, such special alloy steels involve certain inherent disadvantages which have prevented them from achieving widespread use. Specifically, such special alloy steels are extremely difficult to work. Additionally, such special alloy steels are extremely expensive, and this is an important disadvantage when considering the substantial size of the reactors involved.
Accordingly, most prior art reactors of this type have not employed such special alloy steels, but rather have employed simple steels, thereby resulting in substantial installation and repair costs due to premature corrosion damage.
German DT-OS 24 27 530 discloses a methanization reactor wherein the wall of the pressure container is shielded against the high exothermic temperatures that occur during the methanization reaction by means of an inner container containing at least a portion of the volume of the catalyst. The inner container is arranged within the pressure container with an intermediate space therebetween. The gas mixture to be reacted, consisting predominantly of methane and additionally containing carbon monoxide, carbon dioxide, hydrogen and water vapor required for the methanization reaction, is led through an inlet into the intermediate space around the inner container, and thus comes directly into contact with the wall of the outer pressure container. The gas then flows radially inwardly through the catalyst. It will be apparent that this type of reactor is associated with the above discussed disadvantages, namely that the reducing components of the gas are allowed to react on the wall of the pressure container. Therefore, this prior art device is still subject to the above discussed high cost of manufacture or to the danger of premature corrosion damage.
Austrian Pat. No. 215436 discloses a reactor having in the interior thereof plural intermediate limited spaces. The gas is divided into a number of partial flows and supplied to these intermediate spaces. One such gas flow cools the wall of the pressure container from the inside thereof. However, such partial flow is of the reaction gas itself and therefore includes reducing components. Accordingly, the wall of the pressure container is still subjected to the action of such reducing components, and accordingly this prior art device is also subject to the above discussed disadvantages.